NEW YORK (Reuters) - A former lifeguard is suing the New York State Department of Parks and Recreation for doing what he says they have no right to do -- compelling a man in his late 50s to wear Speedo-style swim briefs.

Roy Lester, now 61, began working as a lifeguard at Jones Beach on Long Island more than 40 years ago, but says he lost his weekend job after the state imposed new swimsuit rules in an annual rehiring test that he was uncomfortable complying with.

"People don't want to see old people in Speedos and that's what it comes down to, and I agree with them," Lester told Reuters on Thursday.

His discrimination lawsuit maintains that the parks department has a stated preference for young lifeguards and is using the dress code to force out older members of the corps.

"They want the lifeguards to look young and attractive," he said, pointing to images in marketing and recruitment material and comments by department officials that he said reflected this bias. "So after 40 years you're out of a job."

The parks department declined to comment on the details of the lawsuit, but said it does not discriminate against people because of their age. At the time of the dispute, nearly a third of its lifeguards were between the ages of 40 and 80, it said.

A spokesman for the department also pointed to test rules that allowed candidates to wear board shorts or boxer-style swimsuits as a less skimpy alternative to Speedo briefs.

Lester said he and many men his age preferred to wear jammers, tight-fitting thigh-length shorts, for the speed test required of rehires and new recruits as they have less drag than boxers or board shorts but are more modest than briefs.

In 2007, Lester was not able to take the rehire test because he refused to change out of his jammers after a supervisor said they did not meet requirements. He sued the department over this but lost the case.

The next year, he applied to take the new-hire test. Again his jammers were unacceptable, and the proffered briefs too skimpy. His suggested compromise, to pull the briefs on over his jammers, was rejected.

Lester, a barrel-chested man who still regularly competes in triathlons, says he can easily clear the speed test of 100 yards in 75 seconds. So, he says, there is no question of a particular style of swimsuit giving him an unfair advantage.

He filed a new lawsuit over the new-hire test, which was initially rejected by the state's Supreme Court. But an appeals court allowed it to proceed earlier this month.

Lester earns his living as a bankruptcy attorney, but says he always enjoyed lifeguarding at the weekends because of the camaraderie and a love of exercise and the outdoors that he shares with his children.

"Put it this way, as an attorney I charge $350 an hour and as a lifeguard I made about $14 an hour," he said, adding that the main reason he was proceeding with the lawsuit was to provide a good example to his children of standing up for the principles he believes in.